1. Field of the Invention
This invention relates to a flash light discharge tube control device, and more particularly to a device for controlling the supply of power to a flash light discharge tube attached to a camera body which includes an electrically operated device in addition to the flash light discharge tube.
2. Description of the Prior Art
A flash light discharge tube which is called "strobo" flash light tube is energized by a capacitor. The capacitor is charged before the light is emitted by the discharge of the strobo. In order to charge the capacitor in a short time, a blocking oscillator is used for instance. The circuit including the blocking oscillator, the capacitor for energizing the strobo tube and a power source for supplying power to the blocking oscillator is further provided with a power switch which is closed to supply power to the blocking oscillator before the strobo is energized and a synchronizing trigger switch which is connected with a shutter release mechanism in the camera and is closed to discharge the capacitor and make the strobo tube emit flash light. While the power switch is closed, the charging of the capacitor is started immediately upon discharge thereof.
On the other hand, it has recently been popularized to provide a data printing device in the camera. The data printing device is operated in response to release of the shutter and prints data such as the date of photographing on the film loaded in the camera. The data printing device is also operated by an electric power. Further, it is sometimes desired that a motor drive device for automatically winding up the film in the camera be attached to or incorporated in the camera body. In this case also, the motor drive device is electrically operated. In these cases wherein the camera is provided with an electrically operated device in addition to a strobo device, it is desired that a single power source be commonly used for energizing both the strobo and the additional electrically operated device from the viewpoint of manufacturing cost and size of the camera. Further, if more than one battery is loaded in the camera body, the photographer would have to keep watch on all of the batteries. Therefore, it is desirable that only one power source be provided in a camera body.
The camera provided with only one power source and more than one electrically operated device including a strobo device, however, suffers from a defect in that the additional electrically operated device such as a data printing device is not supplied with a sufficiently high level of power when the charging of the capacitor for discharging the strobo is started. The data printing operation is conducted normally immediately after the release of shutter. After the release of shutter, the charging of the capacitor for discharging the strobo is started. Therefore, in case that the data printing device is operated while the capacitor is charged, there is a possibility of malfunction of the data printing device since the level of the power source is greatly lowered when the capacitor starts to be charged.